This paper presents a new method to improve on block spread OFDM by exploiting time diversity to ensure that the blocks are independent and uncorrelated. Simulation results have shown significant improvement over conventional OFDM and Block Spread OFDM. Disciplines Physical Sciences and Mathematics Publication Details Raad, I. S. & Huang, X. (2006). Exploiting time diversity to improve block sp...

In this paper, we introduce a novel merger of antenna arrays with scanning beam patterns, and Orthogonal Frequency Division Multiplexing (OFDM) systems. Controlled time varying phase shifts are applied to the antenna array elements mounted at the base station with beam patterns directed toward the desired user. This creates a small beam pattern movement called Beam Pattern Scanning (BPS). In ri...

Abstract— Orthogonal frequency division multiplexing (OFDM) is an important technique to support high speed transmission of broadband traffic in wireless networks, especially broadband wireless local area networks (LANs). Based on OFDM, a new multiple access scheme, called OFDM-TDMA with subcarrier allocation (OFDMTDMA/SA), is introduced in this paper. It provides more flexibility in resource a...

In this paper we address the issue of OFDM and PCC-OFDM systems impaired by phase noise (PN). PCC-OFDM is a variation of OFDM in which data is mapped onto adjacent subcarrier pairs. As a result intercarrier interference (ICI) in adjacent subcarriers is cancelled. Phase noise in OFDM causes both ICI and common phase error (CPE). PCC-OFDM reduces the ICI component, but the CPE is unchanged. Theor...

We present a novel bandwidth (BW) efficient orthogonal frequency division multiplexing (OFDM) scheme with adaptive zeropadding (AZP-OFDM) for wireless transmission. Redundancy issues in OFDM based on cyclic prefix (CP), zero-padding (ZP), as well as no guard interval (NGI) systems are analyzed. A novel system design criterion based on the channel matrix condition is studied and applied to the d...

It is necessary to consider fast varying channel for Orthogonal Frequency Division Multiplexing (OFDM) system when OFDM symbols are transmitted over a frequency selective time varying fading channel. The time variations of channel during one OFDM symbol destroy the orthogonality of different subcarriers and result Inter Carrier Interference (ICI), which results in degradation of system performa...

In Cyclix Prefix OFDM (CP) systems, synchronization to the maximal multipath signal generally causes no problem, however, inter carrier interference (ICI) will be introduced in Zero-padding OFDM (ZP-OFDM) systems, e.g, multiband OFDM UWB (MB-OFDM) systems. In this paper, based on the overlap-and-add (ZP-OFDM-OLA) method typically applied in MB-OFDM, we analyze the cause of the ICI and the perfo...

The widespread application of OFDM for local area mobile wireless broadband systems is strongly motivated by the simple equalization it a ords. OFDM's bottleneck of channel-dependent performance was only recently addressed by replacing the cyclic pre x (CP) with trailing zeros (TZ). Such zero-padded OFDM transmissions enable FIR channel-irrespective symbol recovery which results in signi cant B...

Unique Word Orthogonal Frequency Division multiplexing (UW-OFDM) is a variant of the multicarrier technique that has shown better bit error performance compared to cyclic prefixed (CP-)OFDM. Like other techniques, UW-OFDM suffers from high peak-to-average-power ratio (PAPR) problem, which an obstacle ahead practical implementation UW-OFDM. In this letter, generator matrix, inherent UW-OFDM, not...

orthogonal frequency division multiplexing (OFDM) is the most popular modulation technique in modern wireless communication systems. Even though there are many advantages of OFDM, it has two main drawbacks: High peak-to-average power ratio (PAPR) and frequency offset. In this paper the issue of PAPR in OFDM is discussed. Due to the large number of subcarriers used, OFDM systems have a large dyn...